1. Field of the Invention
The present invention relates to an apparatus and method for recognizing persons.
2. Description of the Prior Art
Recently there has been a growing concern in security. A person recognition method utilizing human biometrical information involves identification of a person by discriminating in feature patterns between faces, voiceprints, fingerprints, irises and so on.
The face recognition method, among these, is characterized in that data is readily obtainable through a camera or the like without imposing mental or physical burden on the user.
Although the face recognition method have offered various study reports and literatures, there is a document (xe2x80x9cRecent Research on Face Recognition by Computerxe2x80x9d: Shigeru Akamatsu, The Journal of the Institute of electronics, information and communication engineers, vol. 80 No. 3 pp. 257-266 (1997)) disclosed as a survey document. This document reports that a recognition rate drops to 40-60% in the case that a picture is taken long time after entering an face image.
Japanese Patent Laying-open No. H9-138851 discloses a method of writing face information on a card in order to identify whether it is a card owner or not.
Face feature information on the card has to be rewritten in order to avoid card appropriation. In this method, the data is completely substituted by the recognition data from time to time, resulting in automatic decrease in recognition time interval. However, there is a problem that recognition accuracy will be deteriorated if this method is utilized as it is.
In identification of persons, it is generally preferred to utilize unchangeable fingerprint or the like. However, there involves a problem that fingerprint might inflict a mental displeased feeling upon a user.
Non-contact recognition methods includes the use of voiceprint or face, which is effective in obtaining information to distinguish between persons without burdening on the user.
In the case of face, however, there are aging changes due to lapse of time, such as in hair style, makeup, mustache and physical condition or due to lapse of years, such as in growth and maturity. Further, there exist other variation factors such as change in expression and face direction.
The aging change is also true for voiceprint.
FIG. 2 typically represents a similarity degree to entered data on a some person with respect to time. The horizontal axis denotes days from the entry, while the vertical axis represents a similarity degree expressed in 0.0-1.0, wherein 1.0 means identical. As in the figure, it is general that the similarity degree lowers as the number of days are elapsed. The data entry only once is not sufficient for conducting accurate authentication.
Therefore the present invention provides an apparatus and method for recognizing a person which can reduce the effect of time or year aging change.
The first aspect of the invention is a person recognizing apparatus, comprising: a feature pattern extracting means for extracting a feature pattern obtainable from a person to be recognized; a recognition information calculating means for calculating recognition information containing at least a subspace from the feature pattern extracted by the feature pattern extracting means; a registered information holding means for holding recognition information in multiple manner as registered recognition information; a recognizing means for recognizing the person by using recognition information calculated by the recognition information calculating means or a feature pattern extracted by the feature pattern extracting means and the registered recognition information held in the registered information holding means; a registered information updating means for updating the registered recognition information concerning the person held in the registered information holding means by using the recognition information calculated by the recognition information calculating means or the feature pattern extracted by the feature pattern extracting means.
In the person recognizing apparatus according to the first aspect, the registered information updating means Includes an update determining means for determining a predetermined method as to update of the registered recognition information by the registered information holding means, and an update information creating means for creating new registered recognition information based on the update method determined by the update determining means by using the recognition information calculated by the recognition information calculating means or the feature pattern extracted by aid feature pattern extracting means.
In the person recognizing apparatus according to the first aspect, the registered information holding means holds the registered recognition information in plurality of number concerning one objective person or one group, and the recognizing means recognizes with using registered recognition information in plurality of number concerning the one objective person or the one group in the registered information holding means.
In the person recognizing apparatus according to the first aspect, the update determining means selects recognition information to be updated among the recognition information calculated by the recognition information calculating means based on a predetermined rule, and the update information creating means including an update information creating means for creating new registered recognition information by using the selected recognition information by the update determining means.
In the person recognizing apparatus according to the first aspect, the update determining means determines an update condition based on a time of registering or updating the registered recognition information used by the recognizing means, and the update information creating means including an update information creating means for creating new registered recognition information based on the update condition determined by the update determining means.
In the person recognizing apparatus according to the first aspect, the recognizing means makes recognition using a method of calculating a similarity value, and the update determining means using another method of calculating a similarity value different from the method of calculating a similarity value by the recognizing means.
The second aspect of the invention is a person recognizing method comprising: a feature pattern extracting step to extract a feature pattern obtainable from a person to be recognized; a recognition information calculating step to calculate recognition information containing at least a subspace from the calculation amount extracted by the feature pattern extracting step; a registered information holding step to hold recognition information in plurality of number as registered recognition information; a recognizing step to recognize the person by using recognition information calculated by the recognition information calculating step or a feature pattern extracted by the feature pattern extracting step and the registered recognition information held in the registered information holding step; a registered information updating step to update the registered recognition information concerning the person held in the registered information holding step by using the recognition information calculated by the recognition information calculating step or the feature pattern extracted by the feature pattern extracting step.
In the person recognizing method according to the second aspect, the registered information updating step includes an update determining step to determine a predetermined method as to update of the registered recognition information by the registered information holding step, and an update information creating step to create new registered recognition information based on the update method determined by the update determining step by using the recognition information calculated by the recognition information calculating step or the feature pattern extracted by aid feature pattern extracting step.
In the person recognizing method according to the second aspect, the registered information holding step holds the registered recognition information in plurality of number concerning, one objective person or one group, and the recognizing step recognizes with using registered recognition information in plurality of number concerning the one objective person or the one group in the registered information holding step.
In the person recognizing method according to the second aspect, the update determining step selects recognition information to be updated among the recognition information calculated by the recognition information calculating step based on a predetermined rule, and the update information creating step including an update information creating step to create new registered recognition information by using the selected recognition information by the update determining step.
In the person recognizing method according to the second aspect, the update determining step determines an update condition based on a time of registering or updating the registered recognition information used by the recognizing step, and the update information creating step including an update information creating step for creating new registered recognition information based on the update condition determined by the update determining step.
In the person recognizing method according to the second aspect, the recognizing step makes recognition using a method of calculating a similarity value, and the update determining step using another method of calculating a similarity value different from the method of calculating a similarity degree by the recognizing step.
The third aspect of the invention is a person recognizing program recording means, comprising: a feature pattern extracting function for extracting a feature pattern obtainable from a person to be recognized; a recognition information calculating function for calculating recognition information containing at least a subspace from the calculation amount extracted by the feature pattern extracting function; a registered information holding function for holding recognition information in plurality of number as registered recognition information; a recognizing function for recognizing the person by using recognition information calculated by the recognition information calculating function or a feature pattern extracted by the feature pattern extracting function and the registered recognition information held in the registered information holding function; a registered information updating function for updating the registered recognition information concerning the person held in the registered information holding function by using the recognition information calculated by the recognition information calculating function or the feature pattern extracted by the feature pattern extracting function.
The invention of the first, second or third aspect can update the registration information and suppress against aging change.
The invention of the first or second aspect may perform automatic updating during authentication, thereby eliminating the necessity of troublesome re-registration and preventing the recognition rate due to aging change from lowering.
The invention of the first or second aspect makes it possible to recognize certain one person according to the registered recognition information in plurality of number. There is no requirement to adjust at all times a person condition in a same state, making possible to cope with large variation in the feature pattern of an objective person. Also, it is possible to image recognition with using any of the registered recognition information in plurality of number, further improving convenience.